The objectives of this research involve the synthesis and characterization of synthetic analogues of various heme proteins. The reactions of interest include 1) 0/2, CO and ligand binding by hemoglobin, myoglobin and nonmammalian hemoproteins, 2) 0/2 activation and hydrocarbon hydroxylation by the monooxygenase cytochrome P-450, and 3) the reaction with and reduction of oxidants by catalase and peroxidase. These enzymes are relevant to cardiovascular functioning; drug, hormone and exobiotic metabolism; and to oxidant detoxification and substrate oxidation. Our studies are directed towards an understanding of the molecular mechanisms of these reactions in closely related model metalloporphyrins. We have synthesized, characterized and quantitatively studied the 0/2 and other ligand binding to a series of porphyrinatoiron(II) complexes. Of special interest is our "bis-pocket" porphyrin, which provides protected pockets on both faces of the macrocycle, produces very stable Fe-0/2 complexes, and prevents oxidative degradation. The steric protection of the pocket favors terminal hydroxylation and epoxidation, demonstrating shape-selective molecular recognition. Additional work has been carried out on highly oxidized single atom bridged iron porphyrin dimers which has demonstrated the sensitivity of electronic structure in such systems to the nature of ligation. Proposed work includes the synthesis of oligopeptide-heme complexes as totally synthetic heme proteins; further studies of molecular recognition and substrate specificity on the basis of shape, polarity, charge and hydrogen bonding; and chemical, photochemical, and photocatalytic generation of highly oxidized iron porphyrin complexes. Continuation of our efforts in these areas should lead to a quantitative understanding of the influences which modulate 0/2 and CO binding in protein environments, to the full characterization and isolation of synthetic analogs of high oxidation state heme protein intermediates, and to a closer understanding of substrate shape selectivity and regiospecificity by monooxygenases.